Effects Of Different Stocking Densities Research Articles

Effects of Different Stocking Densities on the Growth, Antioxidant Status, and Intestinal Bacterial Communities of Carp in the Rice–Fish Co-Culture System

Common carp (Cyprinus carpio) is a freshwater fish commonly farmed in rice fields, yet there were few studies on the intestinal functions and microbial community structure of common carp in the rice–carp co-culture system. Therefore, this study aimed to explore the effects of different stocking densities on the growth, antioxidant status, and intestinal bacterial composition of common carp in this system. This study was divided into three different stocking densities, including low density (LD, 10 fish, 52.9 g/m2), medium density (MD, 20 fish, 105.8 g/m2), and high density (HD, 30 fish, 158.7 g/m2), with a culturing period of 60 days. The results indicated that HD treatment inhibited the growth of common carp, as evidenced by the reduced final weight, WG, and SGR. In serum, the TG content in the HD group and the Cor content in the MD group were significantly increased. Meanwhile, HD treatment induced oxidative stress, manifesting specifically as increased SOD and CAT activities in the intestine or serum while reducing Gpx, GSH, and T-AOC in the serum. The 16S rDNA analysis indicated that the Simpson and Shannon indices of intestinal microbiota in the HD group were significantly higher than those in the LD group. At the phylum level, Proteobacteria, Cyanobacteria, and Firmicutes were dominant microbial communities in two groups. In addition, there was a significant difference between the two groups in the abundances of Actinobacterota and Bifidobacterium. Based on growth performances, biochemical indicators, and microbial diversity in rice–carp co-culture, low density (52.9 g/m2) may be more suitable in the rice–carp co-culture systems. In summary, this study contributes to a better understanding of common carp response to different stocking densities in the rice–carp co-culture system.

Haematological, biochemical and oxidative stress parameters of New Zealand rabbits housed at different stocking densities

The aim of this study was to investigate the effects of different stocking densities on oxidative stress, some hematological and biochemical blood parameters in New Zealand rabbits, and to determine the ideal cage area where rabbits can live without being stressed. A total of 36 1–month–old mixed sex New Zealand weaned rabbits were selected for the study. The rabbits were placed in cages at different densities of stocking. Experimental groups were 1 rabbit per cage (C1), 2 rabbits per cage (C2) and 3 rabbits per cage (C3). There was no significant differences between groups in terms of RBC, HGB, HCT, MCV, MCH, WBC, neutrophils, lymphocytes, monocytes, eosinophlis, basophlis, AST, ALT, trigliseride, cholesterol, HDL and LDL parameters (P>0.05). C2 group had lower count of PLT comparing C1 and C3 groups. C1 group had the highest value for MCHC (P<0.05). As oxidative stress parameters, there was no significant differences between IMA and TAS parameters (P>0.05). C2 group had the lowest value in terms of SOD (P<0.05). In conclusion C2 group was determined more advantageous in terms of breeding and welfare, since C1 group does not support social needs of the animals and C3 group leads to increased stress levels due to reduced individual space and restricted movement.

Effects of stocking density on water quality, survival, blood parameters and growth performance of juvenile matrinxã (Brycon amazonicus) in the biofloc system

Biofloc technology (BFT) may be a promising alternative for production of juvenile matrinxã (Brycon amazonicus) as it allows greater fish productivity compared to ponds and is considered an economic and environmentally sustainable system. This study evaluated the effects of different stocking densities on water quality, survival, blood parameters and growth performance of juvenile matrinxã in the biofloc system. Juveniles of 5.89 ± 0.11 g were randomly distributed in five stocking densities (50, 140, 230, 320 and 410 fish ∙ m−3), in triplicate, in a BFT system. Extruded commercial feed (36% crude protein) was offered until apparent satiety four times per day for 61 days. In general, the increase in stocking density resulted in a reduction in dissolved oxygen, pH and alkalinity. Although nitrogenous compounds, total suspended solids, settleable solids and turbidity were greater in higher stocking densities, the water quality parameters were within the recommended range for matrinxã in all treatments. The stocking density had a quadratic effect on the variables specific growth rate, daily weight gain and mean final body weight. For the final stocking density and feed conversion ratio, the effect of stocking density was positive and linear. Survival rates were over 90% at stocking densities >230 fish ∙ m−3. We found a lower concentration of erythrocytes in juvenile matrinxã at the lowest stocking density (50 fish ∙ m−3) and the lymphocyte concentration was higher in the fish kept at 140 fish ∙ m−3 compared to those kept at 410 fish ∙ m−3; however, there was no difference among the other treatments. In conclusion, juvenile matrinxã can be efficiently produced using BFT at stocking densities of 291–293 fish ∙ m−3 or 13.50–13.60 kg ∙ m−3. Although the increase in stocking density is favorable for increasing the biomass and survival of matrinxã, an intensive management of solids and nitrate, as well as alkalinity corrections, are necessary to ensure proper functioning of the production and to avoid mortality of fish due inadequate water quality.

Effects of different stocking densities on growth, nutritional quality, stress and antioxidant response in Labeo rohita; cultured in in-pond raceway system.

A 171-day long experimental trial was undertaken to study intricate physiological response of rohu (Labeo rohita) under stress caused by high stocking density in In-pond raceways system (IPRS). Fingerlings of rohu (initial body weight: 250 ± 1.20 g) were cultured at three different stocking densities; low density (LD) (2.27 kg/m3), medium density (MD) (3.79 kg/m3) and high density (HD) (5.30 kg/m3) in raceways of IPRS production system. Each treatment was in triplicate. Fish growth exhibited a decline in HD treatment statistically as its average weight gain/fish/day was 4.21 g as compared to MD (4.82 g) and LD (4.74 g). Nutritional profile of rohu indicated by the content of crude protein, fatty acids, and profile of amino acids was up to the set dietary benchmarks. Survival rate of fish in all the treatment groups was greater than 99%. The elevated cortisol levels observed in the HD treatment in contrast to the other treatments suggested the presence of stress. The levels of superoxide dismutase, catalase and glutathione peroxidase were also higher in HD as compared to other treatments. However, there were no difference in the level of MDA between the three treatments. Activity of amylase, protease was significantly different in treatment whereas the difference in lipase activity was found to be insignificant. It can be concluded that medium stocking density i.e. 3.79 kg/m3 outperformed the high density (5.30 kg/m3) in different aspects of this study. Nevertheless, additional research is imperative to ascertain whether any intermediate stocking density between medium (3.79 kg/m3) and high (5.30 kg/m3) such as 4 kg/m3, 4.5 kg/m3, or 5 kg/m3, could potentially serve as suitable options for rohu. It is also suggested that brood stock of rohu should be genetically improved to obtain stress resilient fingerlings which will perform better at high stocking density at large scale production level.

83 Effect of stocking density on F1 gilt reproductive performance

Abstract Replacement females are the future of a farm, and their development can impact production. Currently, replacement gilts are housed in many different environments. Stocking density of replacement females is one factor that varies across production systems. Therefore, the objective of this study was to evaluate the effect of different stocking densities on replacement gilt reproductive performance. At 10 wk of age, DNA L241 females (n = 824; DNA Genetics, Columbus, NE) were randomly allotted to finishing pens with 3 different stocking densities. Each stocking density consisted of 12 pens of 0.71 m2 (n = 360), 0.93 m2 (n = 264), and 1.25 m2 (n = 204). Heat detection started at 20 wk of age with fence line exposure for 2 wk at 15 minutes per pen. Within pen boar exposure occurred from 22 to 31 wk of age for a minimum of 10 min per pen. Starting at 20 wk of age, females that exhibited red and swollen vulvas or standing estrus were recorded. Body weight, backfat, and loin depth measurements were collected at estrus detection. A blood progesterone assay was performed on all females at 24 wk of age. Further blood progesterone assays were performed at 27, 29 and 31 wk of age on any female for which progesterone was not detected on previous assays. Females were mated on their 2nd estrus if they were at least 136 kg or on their first estrus if they were over 145 kg. Body weight was recorded at the time of mating. For females that cycled by 31 wk, females in the 0.71 m2 treatment cycled significantly earlier than the 0.93 m2 treatment, 147 vs 153 d post-weaning respectively (P < 0.05). No difference was detected in age at mating; however, gilts in the 0.71 m2 treatment were 5.9 kg and 8.2 kg lighter than the 0.93 and 1.25 m2 treatments respectively (P < 0.01). At 31 wk of age 60% of the 0.71 m2, 71% of the 0.93 m2, and 77% of the 1.25 m2 treatments had cycled according to visual heat detection. However, according to the progesterone assay, at 31 wk of age 75% of 0.71 m2, 81% of the 0.93 m2, and 84% of the 1.25 m2 had cycled. The accuracy of visual heat detection compared with progesterone assay were 79.4% for 0.71 m2, 77.3% for 0.93 m2, and 85.8% for 1.25 m2 treatments. Overall, the 1.25 m2 treatment resulted in heavier females at mating, a greater rate of females cycling, and a more accurate detection of females cycling than the 0.71 m2 treatment. Swine producers can improve the percentage of females detected in estrus and mated in the desired period by providing additional rearing space during gilt development.

Combined intestinal microbiota and transcriptomic analysis to investigate the effect of different stocking densities on the ability of Pacific white shrimp (Litopenaeus vannamei) to utilize Chlorella sorokiniana

Aiming to investigate the impact of different stocking densities on the ability of Pacific white shrimp (Litopenaeus vannamei) to utilize Chlorella sorokiniana (CHL), a 3 × 2 factorial design stocking experiment was used in this study. Specifically, shrimp was fed with two dietary protein sources (fishmeal [FM] and CHL) at low (LSD; 100 per m3), medium (MSD; 200 per m3) and high (HSD; 300 per m3) stocking densities for 8 weeks. The growth performance and resistance to Vibrio parahaemolyticus (1.0 × 107 CFU/mL) of shrimp decreased with the increase of stocking density, but dietary CHL improved this result. Differences between the CHL and FM groups for V. parahaemolyticus resistance were significant only under high-density conditions (P < 0.05). Significant interactions between stocking density and protein source were found on the activities of catalase (CAT), superoxide dismutase (SOD) and phenol oxidase (PO), and the contents of malondialdehyde (MDA) in the hepatopancreas and the activities of intestinal amylase, most of which were significantly different between CHL and FM groups only at high stocking density (P < 0.05). Analysis of 16S rDNA sequencing showed that dietary CHL increased the alpha diversity of intestinal microbiota, inhibited the colonization of pathogenic bacteria and enhanced the abundance of beneficial bacteria. Transcriptomic results showed that at high stocking densities, differentially expressed genes (DEGs) in the FM vs CHL group were mostly upregulated and primarily enriched in immune and metabolic related pathways including Toll, immune deficiency (Imd) and glycolysis–gluconeogenesis pathways. Pearson correlation analysis revealed significant correlation between the top ten intestinal bacteria at the genus level and markedly enriched DEGs, also more were detected under high density situations. In conclusion, CHL has great potential as a novel protein source in the intensive farming of shrimp.

Effect of Stocking Density, Multispecies Probiotics, and Biofloc on Metabolic and Physiological Responses of Puntius sophore in Laboratory Conditions

A 60-day experimental trial was conducted to evaluate the effect of different stocking densities, probiotic supplementation, and a biofloc system on the growth and physiological responses of Puntius sophore in laboratory conditions. P. sophore (8.64 ± 1.24 g) was obtained from the Brahmaputra River, Mymensingh, and immediately transferred to a flow-through water system. In experiment 1, fish were subjected to three treatments (20 fish per 400 L as LD, 25 fish per 400 L as MD, and 30 fish per 400 L as HD), and similarly, in experiment 2, three different types of diets were provided (control diet (D1), biofloc (D2), and a probiotic-containing diet (D3)). Three replications were used in the completely randomized experimental design. Growth parameters, viz. TLG, BWG, FCR, FCE, SGR, RGR, and DGR, were significantly influenced by stocking density and probiotics (p &lt; 0.05). The highest growth rate was observed in LD and in D3. The lowest FCR was also observed in LD and in D3, while highest was in HD (30 fish per 400 L) and in D2. Though stocking density does not impact the blood profile, with the exception of WBC, in the case of feeding regime, WBC, RBC, MCV, MCH, and PLT levels differed significantly (p &lt; 0.05); however, all haematological measures were within the normal range in both experiments, and the fish’s physiological conditions were better in LD and feeding with probiotic supplementation (D3). The results obtained from this study suggested that the welfare of P. sophore is adversely affected by high stocking density and increased growth and physiological conditions when cultured with LD and supplemented with probiotics.

Effects of Stocking Density on the Growth Performance, Physiological Parameters and Antioxidant Status of Juvenile Common Carp (Cyprinus carpio L.) Reared in the Cage system

Stocking density is one of the most important factors influencing growth performance, health status and welfare of fish in aquaculture. This research was carried out to investigate the effect of different stocking densities on growth performance, feed utilization, survival rate, haematology, serum biochemistry and serum antioxidants enzyme responses in common carp juveniles (Cyprinus carpio L.) reared in outdoor cage culture. The fish were randomly stocked in four density groups; 7F fish/0.2m3 (Control group), 14F fish/0.2m3, 21F fish/0.2m3 and 28F fish/0.2m3 in 12 cylindrical cages (0.2m3) in concrete pond, with three cages in each density for 84 days. The results of the 14f density group significantly improved the FW, WG, SGR, FCR, FCE, PER, FI, PI, WBC, RBC, Hct, GSH and SOD activities. The 21F and 28F had significant impacts on FW, WG, SGR, FCR, FCE, PER, FI, PI, glucose, cortisol, ALT, AST, ALP, TG, MDA and GSH increased significantly with increasing stocking density. In contrast, the survival rate, TP, TG, HDL, GPx and SOD activities were significantly decreased. In general, the results demonstrated that the best stocking density is 14F fish/0.2m3 which provided a better growth performance and health status of C. carpio cultured in the cage in the concrete pond.

Correction to: Effect of different stocking densities on growth, oxidative stress, antioxidant enzymes, and hematological and immunological values of European catfish (Silurus glanis L., 1758)

Correction to: Effect of different stocking densities on growth, oxidative stress, antioxidant enzymes, and hematological and immunological values of European catfish (Silurus glanis L., 1758)

Effects of different stocking densities on the development of reproductive and immune functions in young breeder pigeons during the rearing period

ABSTRACT 1. Stocking density (SD) is closely related to animal performance. This experiment was designed to evaluate the development of reproductive and immune functions of young pigeons under different SDs. 2. A total of 288 (half male and half female) 40-day-old pigeons (body weight 400 ± 15 g) were allocated into four groups: High stocking density (HSD; 0.308 m3/bird), standard stocking density (SD; 0.616 m3/bird), and low stocking density (LSD; 1.232 m3/bird) and a caged (control; 0.04125 m3/bird). Every group had six replicates of the same sex. 3. The results showed that caged male pigeons had the highest testis index, testosterone content, and gene expression of the androgen receptor gene. LSD treatment induced the highest concentrations of oestradiol, progesterone and mRNA levels of reproductive hormone receptor genes in female pigeons. In male pigeons, the spleen index (organ weight calculated as a percentage of total body weight) showed a peak level (0.09 ± 0.020) in the LSD group, and the thymus index peaked (0.23 ± 0.039) in SD group. However, the index for ovary, spleen, thymus and bursa of Fabricius in female pigeons showed no significant changes among different groups. 4. The IL-1β, IL-8, IFN-γ, TGF-β and toll-like receptor 2 (TLR-2) mRNA levels reached their maximum values in both male and female pigeon spleens in the LSD group. 5. Young male pigeons housed in cages showed increased testicular development while low stocking density increased the development of reproductive function in young female pigeons. A larger activity space could help enhance the immune function of both male and female pigeons.

EFFECT OF STOCKING DENSITY ON PRODUCTIVE PERFORMANCE OF JUVENILE OF THE BLACKSTRIPE CICHLID Vieja fenestrata (CICHLIFORMES: CICHLIDAE)

&lt;p class="18AbstractandKeywords"&gt;&lt;span class="Ninguno"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Background:&lt;/span&gt;&lt;/strong&gt;&lt;/span&gt;&lt;span class="Ninguno"&gt;&lt;span lang="EN-US"&gt; Native fish species are a developing alternative for sustainable aquaculture worldwide and in Mexico, the southern region is leading the efforts in freshwater species. &lt;strong&gt;Objective:&lt;/strong&gt; To assess the effect of different stocking densities on the productive performance of native fish juveniles of blackstripe cichlid (&lt;em&gt;Vieja fenestrata&lt;/em&gt;).&lt;em&gt; &lt;/em&gt;&lt;strong&gt;Methodology:&lt;/strong&gt; A one-factor randomized experimental design was used, evaluating in triplicate four stocking densities, 0.5 (L), 2 (M), 4 (H) and 6 (S) juvenile L&lt;sup&gt;-1&lt;/sup&gt;. The experiment lasted 30 days. Wet weight and total length were registered every 15 days and growth performance indices were obtained. &lt;strong&gt;Results:&lt;/strong&gt; Growth and survival were superior (P&amp;lt;0.05) for densities L and M. However, the M density showed a higher (P&amp;lt;0.05) growth rate, weight gain, and condition factor. &lt;strong&gt;Implications:&lt;/strong&gt; The stocking density showed an apparent effect on the growth and survival of juveniles of the blackstripe cichlid, with the M density showing the best results; however, a cost-benefit assessment is required before starting production of this tropical native species. &lt;strong&gt;Conclusion:&lt;/strong&gt; Our results suggest that a territorial and/or food competition was probably responsible for the survival and growth obtained. Although more studies are required, it appears that &lt;em&gt;Vieja fenestrata&lt;/em&gt; showed the typical patrons of behaviour of another most famous cichlids, as Nile tilapia, with high levels of aggression that depend on stoking density. &lt;/span&gt;&lt;/span&gt;&lt;/p&gt;

Effect of stocking density on larval performance and post-larvae settlement of clam Ruditapes decussatus (Linnaeus, 1758) in bivalve hatchery production

Larval rearing is a critical phase in bivalve hatchery production and plays a crucial role in the success of spat production. Therefore, understanding the effect of density on larval performance and post-larvae settlement is crucial for optimizing and improving the success of bivalve hatchery production. This study aimed to evaluate the effect of different stocking density on larval performances and settlement rate of clams Ruditapes decussatus. Three different larval rearing densities (10, 20, and 40 larvae/mL) and four settlement densities (35, 70, 100, and 140 larvae/cm²) were studied. The results regarding larval performance showed that high density resulted in low larval survival (18% for D40) compared to low and moderate densities (23% for D10 and 26% for D20, respectively). In terms of post-larvae settlement, a density of 35 larvae/cm² exhibited the highest fixation rate (36%) compared to 33%, 18%, and 9% at 70, 100, and 140 larvae/cm², respectively. Statistical analysis revealed a significant effect of larval density on both survival and growth (F = 11.79, p &lt; 0.05; F = 18.63, p &lt; 0.05, respectively), as well as a highly significant effect on settlement (F = 14.88, p &lt; 0.001). Overall, it is advisable to maintain moderate densities during both larval performance and post-larvae settlement for seed production of R. decussatus in the hatchery.

Stocking density affects culture performance and economic profit of adult all-female Chinese mitten crabs (Eriocheir sinensis) reared in earthen ponds

As female Chinese mitten crab (Eriocheir sinensis) generally offer the higher edible yield, greater nutritional value, and consequently, higher market price compared to males, therefore all-female monosex culture has been popularized for the farming E. sinensis. However, the optimal stocking density remains unknown for all-female culture of E. sinensis. The present study was conducted to evaluate the effect of different stocking densities (D1.3: 1.3 inds/m2, D1.9: 1.9 inds./m2, D2.5: 2.5 inds./m2 and D3.8: 3.8 inds./m2) on growth performance, gonadal development, and economic profits of all-female E. sinensis during nine months culture period. The results showed that all growth parameters including mean body weight, body weight gain (BWG) and specific growth rate (SGR), exhibited an inverse relationship with stocking density. However, stocking density did not have a significant effect on the percentage of puberty molting, gonadosomatic index (GSI) and hepatosomatic index (HSI). At the end of the experiment, the survival rate significantly decreased with the increasing stocking density, while both final production yield and economic feed conversion ratio (eFCR) significantly increased with stocking density (P < 0.05). Profitability analysis showed that total cost and total return increased significantly with the stocking density, but the highest net profit (129.68 × 103 CNY/ha) and return-on-investment (ROI, 87.65%) were achieved at the D2.5 group. Overall, these results suggested that the optimal stocking density might range from 1.9 to 2.5 individuals/m2 in grow-out ponds for all-female mono-culture of E. sinensis.

Effects of different stocking densities and feeding frequencies on growth, physiological and biochemical indexes, and intestinal microflora of largemouth bass (Micropterus salmoides) under land-based round pond

Land-based Round Pond is an emerging and efficient aquaculture technique widely adopted in Southwest China. To study the effects of stocking density and feeding frequency on growth, oxidative stress, physiological characteristics, and intestinal flora of largemouth bass (Micropterus salmoides) in Land-Based Round Pond, 3 × 2 two-factor treatment groups were set with three stocking densities (30, 40, and 50 fish/m3) and two feeding frequencies (2 and 3 times/day). Largemouth bass (initial weight of 155.62 ± 2.43 g) were stocked for 60 days. The yield of 30 fish/m3 groups were close to 40 fish/m3 groups, but the 30 fish/m3 groups demonstrated significantly higher growth rate, condition factor and lipid content compared to other density groups with a lower feed conversion ratio (p < 0.05). The feeding frequency of 3 times per day resulted in higher growth rate than 2 times per day with a higher feed conversion ratio (p < 0.05). Physiological and biochemical analyses showed that levels of TC, TG, lysozyme, ALP, T-SOD, CAT, AOC, lipase, and trypsin were significantly higher in the 30 fish/m3 groups than those of other density groups, while MDA content were highest in the 50 fish/m3 groups than other groups (p < 0.05). The T-SOD and CAT activity were significantly higher in the 3 times per day groups than those in the 2 times per day groups (p < 0.05), and no significant effect of feeding frequency on the immunity was observed. No pathological changes were found in muscle and intestinal histology, but infiltration of hemocytes was found in liver in the 50 fish/m3 groups. In intestinal microbial analysis, the 40 and 50 fish/m3 density groups had a higher relative abundance of Proteobacteria, suggesting a higher probability of disease occurrence and an unstable intestinal microflora. These results demonstrate that the optimal stocking density for largemouth bass in Land-Based Round Ponds is 30 fish/m3 (155 g/fish) at a size stage ranging from 155.62 g to 353.83 g, with the optimal feeding frequency of 3 times per day. This study provides a theoretical basis for the development of Land-Based Round Ponds.

Effect of different stocking densities on growth, oxidative stress, antioxidant enzymes, and hematological and immunological values of European catfish (Silurus glanis L., 1758)

Effect of different stocking densities on growth, oxidative stress, antioxidant enzymes, and hematological and immunological values of European catfish (Silurus glanis L., 1758)

Effects of different stocking densities on organ development, blood biochemical indices, and antioxidative status of breeder pigeons during the rearing period

The present experiment was conducted to investigate the effect of different stocking densities on the organ development, blood biochemical indices, and antioxidative status of breeder pigeons during the rearing period. A total of 280 (halfmaleandhalffemale) 40-day-old young pigeons were allocated into 4 groups, including 3 experimental groups (in compartments of the flying room): the high stocking density (HSD) (0.308 m3/bird), standard stocking density (SD) (0.616 m3/bird), and low stocking density (LSD) (1.232 m3/bird) and a caged control (0.04125 m3/bird). The results showed that the contents of corticosterone and heat shock protein 70 in males and the corticosterone content in females were higher in the control than in the other groups. The relative weight of liver, lung, and gizzard in males of the HSD group was the highest among the 4 treatments, whereas the abdominal fat index in the control group was higher than those in the other 3 treatments. Body weight and the relative weight of liver and abdominal fat in female pigeons in HSD group increased significantly. The levels of serum urea nitrogen and uric acid in pigeons of LSD group increased significantly, while the concentration of total cholesterol and the activity of alanine aminotransferase were higher in the control group. Ion (K+, Ca2+, and Na+) concentrations in female pigeon serum were also elevated in the control. The activity of antioxidant enzymes, including the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase in pigeon breast muscle and liver had different degrees of inhibition when the space room was crowded. Moreover, the level of malondialdehyde in the liver of male caged pigeons was higher than that in the other treatments. In summary, rearing in cages or at a high density caused stress responses in the breeder pigeons. The stocking density of breeder pigeons during the rearing period should be ranged from 0.616 m3/bird to 1.232 m3/bird.

Assessment of zootechnical parameters, intestinal digestive enzymes, haemato-immune responses, and hepatic antioxidant status of Pangasianodon hypophthalmus fingerlings reared under different stocking densities

A 3-month experiment was designed to investigate the effects of different stocking densities on growth, stress markers, intestinal digestive enzymes, hepatic antioxidant biomarkers, serum immunity, and survivability of striped catfish, Pangasianodon hypophthalmus. The relationship between fish stocking densities and water quality parameters was also assessed. Healthy fish (n = 1260 individuals, 17.52 ± 0.20 g) were raised in twelve fiberglass tanks. Triplicate fish groups with stocking densities of 60, 90, 120, or 150 fish per 1 m3 were designed, further referred to as SD60, SD90, SD120, and SD150 groups. Fish feeding was done using a commercially purchased well-balanced diet three times per day with a feeding rate of 3% of the wet fish weight. Results revealed that un-ionized ammonia, nitrite, and pH were significantly elevated, and dissolved oxygen levels were decreased significantly with increasing the stocking densities. The survival rates and growth significantly decreased with increasing fish stocking densities. The intestinal lipase, protease, trypsin, and amylase enzymes decreased significantly (P < 0.05) along with increased stocking densities. Moreover, significant decreases were noticed in total protein, lysozyme activity, and globulin levels when the stocking density was higher than 60 fish/m3. Conversely, serum stress biomarkers (such as blood glucose and cortisol), transaminases, alkaline phosphatase, and blood urea nitrogen were significantly elevated with increasing stocking densities. Hepatic CAT, SOD, and T-AOC were decreased; meanwhile, hepatic MDA levels were significantly increased, together with the stocking rates. In the end, we found that the SD150 group recorded the lowest growth rates, immune responses, and antioxidant capacity and the highest stress markers as blood glucose and cortisol. In this context, we can conclude that the stocking 60 fish/m3 resulted in better growth, survival, immunity, antioxidant status, and overall performances of striped catfish.Graphical

Effect of Stocking Density on Growth, Water Quality Changes and Cost Efficiency of Butter Catfish (Ompok bimaculatus) during Seed Rearing in a Biofloc System

Biofloc technology is a modern-day high-density fish culture system employing heterotrophic conversion of nitrogenous waste into useful flocs for water quality control and improved welfare. However, optimization of the stocking density for the target species during seed rearing is the key to a successful farming operation. The study evaluated the effect of different stocking density on the growth, feed utilization, digestive physiology and economics in a biofloc-based seed rearing of butter catfish, O. bimaculatus. Advanced fry (1.21 ± 0.08 g) was reared in a zero-water exchange biofloc system for 90 days at stocking densities of 0.5 g/L(T1), 1.0 g/L(T2), 1.5 g/L(T3) and 2.0 g/L(T4). The observed water quality indicates a reduction in DO and pH in T4, while the total ammonia nitrogen and nitrite levels remained low in T1. Among the groups, highest weight gain was noticed in the lowest stocking density (0.5 g/L) (p &lt; 0.05), which coincides with a better feed conversion ratio. Similarly, the digestive enzyme (protease, amylase, and lipase) secretion was higher in T1. Profitability assessment describes the possibility of low profit in T4, in the case where the fish’s sale price is based on harvested size. T1 showed higher individual growth and higher profit. Overall, a low stocking density of 0.5 g/Lis optimum for augmenting growth, feed utilization, physiological function and economic performance of O. bimaculatus. The study provides direction for a low-stocking oriented ecological and economically sustainable method of seed production of butter catfish in a biofloc system.

Effect of different stocking density on some growth performance and skin color of Koi carp fry (Cyprinus carpio var. Koi Linnaeus, 1758) reared in concrete, earthen and fiberglass ponds

Effect of different stocking density on some growth performance and skin color of Koi carp fry (Cyprinus carpio var. Koi Linnaeus, 1758) reared in concrete, earthen and fiberglass ponds

Comparative effect of stocking density and flock size on performance and egg quality of laying hens in conventional and furnished California cages

Two experiments were carried out with an objective to test the comparative performance of laying hens reared in conventional California cages vs furnished California cages with regards to production performance, egg quality parameters and immune status. Experiments were conducted at Poultry Research and Training Centre, Department of Poultry Science, Nagpur Veterinary College during 2019-21. Commercial White Leghorn (BV300) hens (n =72) in each experiment were assigned into two treatments with six replicates in conventional and furnished California cages, and reared for a 20 week period. The furnished cages (FC) are provided with perches, nesting area and scratch pad to meet the natural behaviour of the birds. There were two different treatments viz. 548 cm2/b×6 birds and 645cm2/b×6 birds to see the effect of different stocking density in cages. The performance of the laying hens reared in furnished cages were recorded and compared with findings of birds reared in conventional California cages (CC). The results showed that body weight, weight gain, hen day egg production percentages, feed : egg ratio, egg weight and proportion of broken eggs and dirty eggs were not significantly affected by cage types. However, Haugh unit and albumen height of the eggs from furnished cages hens were significantly higher than those from the conventional California cage hens. While H/L ratio and corticosterone values were significantly lowest in furnished cage system birds. It can be concluded from study that the layer birds can be reared in stress free condition in furnished cage system.